Brief announcement: on the quest of optimal service ordering in decentralized queries

This paper deals with pipelined queries over services. The execution plan of such queries defines an order in which the services are called. We present the theoretical underpinnings of a newly proposed algorithm that produces the optimal linear ordering corresponding to a query being executed in a decentralized manner, i.e., when the services communicate directly with each other. The optimality is defined in terms of query response time, which is determined by the bottleneck service in the plan. The properties discussed in this work allow a branch-and-bound approach to be very efficient.